body {
    display: flex;
    flex-direction: column;
    align-items: center;
    font-family: Arial, sans-serif;
}

.grid {
    display: grid;
    grid-template-columns: repeat(5, 50px);
    gap: 5px;
    margin-bottom: 20px;
}

.cell {
    width: 50px;
    height: 50px;
    background-color: #ccc;
    display: flex;
    justify-content: center;
    align-items: center;
    cursor: pointer;
    border: 1px solid #999;
}

.on {
    background-color: yellow;
}
